Aptitude - Problems on Trains - Discussion

Speed = 15mtr/hr.
15*20 = 15 * 36,
300 = 540.
= 540 - 300.
Length = 240.

As we know Distance = Speed x Time.

Let's find the length of the train --> to find the distance of a train we have to multiply the speed of the train by the time taken by the train to cross a man or pole. so it comes like 15 x 20 = 300 meters.

So, the length of the train is 300 meters

Now when we multiply the train speed with the time taken to cross the platform..... we get the whole length of the train and also the platform length. LIKE --> 15 x 36 = 540 meters .

Now, this length is the whole length of the platform and the train.

To find the platform length subtract the train length that we found out with the whole length
300 - 540 = 240.

240 is the length of the platform.

Why didn't we added the length of the man? Please explain.

Answer 240m is possible only if the man is standing at the end of the station.

Am I right or wrong? Please anyone clarify.

I have solved this problem in a different way, is this the right way to solve it?

Speed=15 m/sec.
Total length of train is 300m,
let length of the plateform be x m,
total distance = speed * time,
x + 300 = 15*36,
x + 300 = 540,
x = 240m.

Why they have taken 20 sec. Can we take 30 sec also? Please explain.

Why we, not multiple 15 * 36 instead we multiple 15 * 20? Please explain.

t1-t2 = 36 - 26 = 16.

We know 54 x 5/18=15,
So putting in formula s=d/t.
15 = d/16, where d is taken as length here;
d = 15 * 16,
= 240.

You can multiply 15 * 36 which gives you 540m then x be the length of the platform therefore as speed = distance upon time 540 +x/20 = 15.

x = 240m.

Shortcut method:-

Train + Platform = 36 sec.
Train = 20sec.
Extra it takes 16 sec to travel platform.
Covert kmph to m/s because we need answer in m/ s.

54kmph*5/18 = 15m/s.
15* 20 = 300m train length.
It takes 20 sec ---> 300m
16sec ---> ?????
Less by more concept 16/20 *300 = 240 m.